Airport security checkpoint lines are the very definition of a “necessary evil”. Everyone hates the long waits and the awkward disrobing dances as you rid yourself of all your shoes, smartphones, metal, etc. Yet, we’re eternally grateful when crazy people with samurai swords don’t fly coach. Now, a new breakthrough in nanotechnology could help ease our collective dread for airport security, at least a little bit.
A team of researchers from UC Berkeley discovered a way to detect “minute concentrations of explosives,” according to a press release. This new small laser sensor can be packed into a handheld device and basically out-sniff any canine alternative. The team’s findings were published in Nature Nanotechnology on Sunday.
These claims of substantial improvements to laser-powered sniffing were put to task when the team sampled a couple of explosives, like 2,4-dinitrotoluene (more commonly known as DNT) and picked up on airborne concentrations of .067 parts per billion. To put a mental image to that accomplishment, that’s the same as picking out a single blade of grass on a football field.
So how exactly does it work? Think of this nano-device’s structure as a bomb-detection sandwich, so from the top down: a layer of cadmium sulfide (a semiconductor), magnesium fluoride, and a sheet of silver. Surface defects on the semiconductor, which the team designed with nitro groups (DNT, TNT) in mind, interact with explosive molecules. Those interactions return in the form of an intense light signal. The chemical secret is that explosives generally have an electron deficiency. The stronger the deficiency, the stronger the reaction.
However, terrorists are a notoriously slippery bunch and have the lethal habit of using alternatives, like pentaerythritol tetranitrate, or PETN. This chemical cocktail can fool x-rays and is one of the reasons you have to take your shoes off at airports. But the team theorizes that even this well-hidden substance won’t escape their new tech because PETN has an even higher electron deficiency than the testing group.
“Optical explosive sensors are very sensitive and compact,” says Xiang Zhang, a professor of mechanical engineering who led the study. “The ability to magnify such a small trace of an explosive to create a detectable signal is a major development in plasmon sensor technology, which is one of the most powerful tools we have today.”
This isn’t the first time we’ve been promised shorter airport security wait times. In 2011, a professor from MIT considered a similar process but instead used bee venom on a one-atom thick carbon rod. We’ve even heard of bomb-detection plants that change colour when explosives are present.
For now, our best bomb-fighting tech isn’t really tech at all. Trained canine units and swabbing are still the most effective methods, but maybe Zhang and his team can give weary travellers some much-needed peace of mind. [Motherboard]